Academic literature on the topic 'Binary bandwidth control of WDM'

Passive optical network (PON) is considered as an attractive fiber-to-the-home (FTTH) technology. Wavelength division multiplexed (WDM) PON improves the utilization of fiber bandwidth through the use of wavelength domain. A cost-effective solution in WDM PON would use the same components in each optical networking unit (ONU), which should thus be independent of the wavelength assigned by the network. Optical carriers are distributed from the head-end office to different ONUs to produce the upstream signals. Various solutions of colorless ONUs will be discussed. Although the carrier distributed WDM PONs have many attractive features, a key issue that needs to be addressed is how best to control the impairments that arise from optical beat noise induced by Rayleigh backscattering (RB). Different RB components will be analyzed and RB mitigation schemes will be presented. Finally, some novel PONs including signal remodulation PONs, long reach PONs and wireless/wired PONs will be highlighted.

Robust mobile middlewares are crucial for online applications as they provide solutions for the core issues of mobility, data interoperability, and security. This chapter describes our experience in designing such middlewares for one of the largest Australian transport companies (CMS Transport Systems). We focus on the design of a predicate-based caching technique for mobile object-based middlewares that optimises the performance of the mobile medium by better utilising the available bandwidth. Several caching techniques have been proposed to improve system and application performance. Such techniques, along with consistency control mechanisms, are used to reduce the communication load between clients and servers, which is particularly important in wireless networks. Caching techniques are generally classified as either ID-based or predicate-based. In this chapter we propose a predicate-based caching scheme, in which the predicates are used in combination with updates and are broadcast by servers in a set of appropriate messages called cache invalidation reports. Each report/message contains information about the data items that have been updated in the server during a given period. A function mapping the predicate into binary representation is defined for each attribute. Because not all updates are relevant to a cache, there is a matching algorithm for detecting relevancy between the cache predicate and the predicates in the cache invalidation reports. The predicate-based cache invalidation reports inform the client cache manager concisely about items that need to be refreshed and about those that need to be discarded, and ensure efficient bandwidth usage.

In wireless communication environments, backoff is traditionally based on the IEEE binary exponential backoff (BEB). Using BEB results in a high delay in message transmission, collisions and ultimately wasting the limited available bandwidth. As each node has to obtain medium access before transmitting a message, in dense networks, the collision probability in the MAC layer becomes very high when a poor backoff algorithm is used. The Logarithmic algorithm proposes some improvements to the backoff algorithms that aim to efficiently use the channel and to reduce collisions. The algorithm under study is based on changing the incremental behavior of the backoff value. The Binary Exponential Backoff (BEB) is used by the Local Area Networks standards, IEEE 802.11, Medium Access Control (MAC). BEB uses a uniform random distribution to choose the backoff value; this often leads to reducing the effect of window size increment. This paper carries out a deeper study and analysis of the logarithmic backoff algorithm that uses logarithmic increment instead of exponential extension of window size to eliminate the degrading effect of random number distribution. Results from simulation experiments reveal that the algorithm subject to study achieves higher throughput and less packet loss when in a mobile ad hoc environment.

This paper presents the design, model identification and control of a parallel-kinematics XYZ nano positioning stage for general nano-manipulation and nano-manufacturing applications. The stage features a low degree of freedom monolithic parallel kinematic mechanism with flexure joints. The stage is driven by piezoelectric actuators and its displacement is detected by capacitance gauges. The control loop is closed at the end-effector instead of the each joint, so as to avoid calibration difficulties and guarantee high positioning accuracy. Instead of a single input and single output (SISO) sys